"It was devastating," Vincent Kartheiser tells TVGuide.com. "There were tears and sadness. But I'm happy that Jared [Harris] had a nice big ending and something that will impact the characters hopefully for the next two seasons. His character will kind of remain with the show even though he won't be there alive."Just how much impact will the ghost of Lane have on Mad Men's finale, interestingly titled "The Phantom"? In our Q&A below, Kartheiser tackles that question and also looks back at a number of questionable decisions (Joan! Rory Gilmore!) his character Pete Campbell made this season. Plus: Kartheiser tells us why Pete will never be fully content.I imagine everyone will be impacted by Lane's death somehow. Do you think Pete will feel guilty at all?Vincent Kartheiser: There's no way that he can't be affected. But at what level does Pete feel guilt? Does he have that blue blood, "I'm not going to feel guilty [because] everyone makes their choices" [attitude], or is he actually going to have some remorse about how he acted this season? Those are questions I had when I read the script, and the audience will discover [the answers] very soon.

He obviously isn't wallowing in guilt over asking Joan (Christina Hendricks) to prostitute herself for the company.Kartheiser: He can stomach what he thinks they have to do to get ahead. He really wanted to take that bull by the horns and he was OK being the one who brought it to Joan, brought it to the partners, and who didn't let it die when Don [Jon Hamm] left. [Pete has] the ability to say "I'm willing to be the guy who's responsible for this person's emotions, and for this company's success." All industries are dirty and there are dirty secrets. What's the old saying? "Most great corporations were started with a crime?" So it's not unheard of. It's not off the wall.But it was arguably a new low for Pete. However, earlier this season we almost felt bad for Pete when he broke down in the elevator. Are you glad we got to see that other side of Pete?Kartheiser: They're both great parts of him, but they're both also based directly on his ego. He's not crying for some noble cause. He's crying for himself. He's crying for his own lack of self-worth, or his inability to get recognized or protected by people he considers his friends. There's a bit of self-pity involved in it.

How much of Pete's desire to land Jaguar is driven by the idea of escaping his home life? He's obviously miserable in the suburbs.Kartheiser: We need to feel wanted and loved. I think we all have a desire for a sense of magic and spontaneity in our lives. This season Pete's been searching for a woman to give that to him. But I don't know how connected that is to his ambition because the ambition has stayed pretty consistent even when he was happy with Trudy [Alison Brie].

But the other women Pete's sleeping with aren't necessarily improving his life.Kartheiser: He's got to be wanted. He needs more, and he needs something new and fresh. He's looking for something to fulfill that part of his life. ... He's looking for someone to look at him and say, "You're amazing, you really are my king." He needs that outlet. He needs to feel needed.

Don's line in the pitch to Dow Chemical — "Happiness is a moment before you need more happiness" — seems to sum Pete up pretty well.Kartheiser: Right. That's part of the reason he's also looking for things outside of his marriage and outside of his work. He's being sent skis by these companies he doesn't even represent, and people are talking about him like he's a great account man. But ultimately, it doesn't fulfill him. That feeling he's been chasing, that recognition — well, now he gets a little, and it's not enough. He wants the wife, he wants the kids, he wants to make her happy. And then he has it, and he's like, "Well, that's not enough."

Do you think that will ever change for Pete?Kartheiser: It's not going to go away because even though you know that it's not going to make you fulfilled, you don't want to lose it. There is a double-edged sword to it. You start to realize you're doomed to an ambitious life that [always] leads to yet another mountain to climb.

So, given all that, where is Pete's head at in the finale?Kartheiser: Pete's flustered. I think at this point, he's shaken by what's happened with Lane. He's confident, but only business-wise. The Jaguar account is a good thing, but other than that, things haven't been so smooth sailing for Pete this season. So I wouldn't suspect he's going to be in more of a stable place then he has been.

The episode description says Pete meets an interesting stranger on the train. Any hints?Kartheiser: We have a lot of guest stars this year, and there's another great one coming up.